Recently, along with the rapid development of the display technology, an LTPS TFT has emerged so as to replace an original amorphous silicon (a-Si) TFT. The LTPS TFT has various advantages. For example, its electron mobility may be more than 200 cm2/V-sec, so it is able to, on one hand, effectively reduce an area of the TFT and improve an aperture ratio, and on the other hand, reduce the overall power consumption while increasing a display brightness value. For another example, due to the relatively high electron mobility, it is able to integrate a part of driving circuits into a substrate, so as to reduce the number of driving integrated circuits (ICs), thereby to significantly improve the reliability of a liquid crystal display (LCD) panel and remarkably reduce the manufacture cost. Hence, the LTPS TFT has currently become a research focus in the field of display technology.
During the manufacture of the LTPS TFT, in order to form an excellent electrical connection between a source/drain electrode and an LTPS active layer and suppress the occurrence of leakage current, it is necessary to dope the LTPS active layer through an ion injection process, so as to form a heavily-drain-doped region and a lightly-drain-doped region. Usually, a half-tone or gray-tone mask plate is adopted in the related art so as to heavily and lightly dope the LTPS active layer. However, it is found that a p-Si layer may be damaged or oxidized, and thereby a display effect may be adversely affected.